Time: 319 ms (48.74%), Space: 10.6 MB (70.32%) - LeetHub

Author: fizaayesha

0079-word-search/0079-word-search.cpp

@@ -0,0 +1,44 @@
+class Solution {
+public:
+    bool found=false;
+    vector<pair<int,int>> dir={{1,0},{-1,0},{0,1},{0,-1}};
+    bool isSafe(int i, int j, int n, int m, vector<vector<bool>> &vis){
+        return i>=0 && j>=0 && i<n && j<m && !vis[i][j];
+    }
+    void solve(int i, int j, int n, int m, vector<vector<bool>> &vis, vector<vector<char>>& board, string &word, int ind){
+        if(found){
+            return;
+        }
+        if (board[i][j] != word[ind]) return;
+        if(!isSafe(i,j,n,m,vis)){
+            return;
+        }
+        if (ind == word.size() - 1) { // last char matched
+            found = true;
+            return;
+        }
+        // cout<<"1 call"<<endl;
+        vis[i][j]=true;
+        for(int k=0;k<4;k++){
+            // cout<<"2 call"<<endl;
+            int newI=i+dir[k].first;
+            int newJ=j+dir[k].second;
+            if(isSafe(newI,newJ,n,m,vis)){
+                solve(newI,newJ,n,m,vis,board,word,ind+1);
+            }
+        }
+        vis[i][j]=false;
+    }
+    bool exist(vector<vector<char>>& board, string word) {
+        int n=board.size(),m=board[0].size();
+        int i=0,j=0,ind=0;
+        vector<vector<bool>> vis(n,vector<bool>(m,false));
+        for (int i = 0; i < n; i++) {
+            for (int j = 0; j < m; j++) {
+                solve(i, j, n, m, vis, board, word, 0);
+                if (found) return true;
+            }
+        }
+        return false;
+    }
+};